“We weren’t Camelot,” James Earl Carter IV, grandson of Jimmy, once told the Atlanta Journal-Constitution. “Far from it, actually. We were farmers.” This is the same James Earl Carter IV, of course, who helped bruise Mitt Romney last week by getting the secretly recorded “47 percent” video into the hands of Mother Jones. And he’s not the only descendant of the 39th president to show a Kennedy-esque willingness to throw himself into a political fight.